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Suitability of Translocation Sites for Florida Burrowing Owls: Prey Availability and Diet
Ronald J. Sarno, Per A. Nixon, Brian K. Mealey, Ronald E. Concoby, Robert J. Mrykalo, and Melissa M. Grigione

Southeastern Naturalist, Volume 11, Issue 4 (2012): 755–764

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2012 SOUTHEASTERN NATURALIST 11(4):755–764 Suitability of Translocation Sites for Florida Burrowing Owls: Prey Availability and Diet Ronald J. Sarno1,*, Per A. Nixon2, Brian K. Mealey3, Ronald E. Concoby4, Robert J. Mrykalo5, and Melissa M. Grigione6 Abstract - We investigated if relative abundance of invertebrate prey for Athene cunicularia floridana (Florida Burrowing Owl) differed between two pre-translocation (i.e., non-mined) sites and one translocation (i.e., reclaimed mine) site. We trapped a combination of 21 arthropod families and orders. We observed some differences among non-mined sites and the reclaimed mine site in invertebrate prey abundance and owl diet. Fewer than 50% (10 of 21) of trapped prey items were present in pellets, suggesting that our traps may have limited capture of particular prey. Additionally, it appears that owls were hunting in nearby aquatic habitats due to the remains of frogs, turtles, and crayfish in pellets. The general similarity in prey abundance and diet between the pre-translocation and translocation sites suggests that reclaimed mine sites may serve as adequate refugia for Florida Burrowing Owls. However, more work is needed to determine to verify the general applicability of our results. Introduction Phosphate mining disturbs 2000 to 2500 ha/year in Florida, with nearly 2/3 of this area characterized as upland or mesic habitat (Florida Department of Environmental Protection 2005). The vast majority of upland habitat is improved pasture—pasture in which agricultural grasses or other forage species have been introduced in order to increase the volume and quality of available grazing forage for livestock (Florida Department of Transportation 1999). These habitats have also been found to support populations of Athene cunicularia floridana (Molina) (Florida Burrowing Owl) (Mealey 1997, Mrykalo et al. 2007), which have been state listed as a species of special concern by the Florida Fish and Wildlife Conservation Commission (FWC) since 1979 (Florida Department of State 1979) as a result of population declines due to continued habitat loss (Birnhak and Crowder 1974, Ewel 1990). The FWC has recently recommended that the Florida Burrowing Owl be upgraded to a state-listed threatened species (Florida Fish and Wildlife Conservation Commission 2011). Mining activities in upland habitats generally result in the displacement of Florida Burrowing Owls. As a result, mining companies are required to restore mined sites in accordance with local, state, and federal mandates (Florida 1Department of Biology, 228 Gittleson Hall, 114 Hofstra University, Hempstead, NY 11549. 2Department of Environmental Science and Policy, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620. 3Institute of Wildlife Sciences, 16531 SW 81st Avenue, Palmetto Bay, FL 33157. 4Eco-Logic Restoration Services, LLC, 1517 Orange Avenue, Eustis, FL 32726. 5PO Box 292452, Tampa, FL 33687. 6Graduate Program in Environmental Science, Department of Biology, Pace University, Pleasantville, NY 10570. *Corresponding author: e-mail-Ronald.Sarno@hofstra.edu. 756 Southeastern Naturalist Vol. 11, No. 4 Statutes Chapter 378 and Florida Administrative Code Chapter 62C-16). Restoration includes type-for-type, acre-for-acre replacement of specific habitats, including Paspalum notatum (Alain ex Flüggé) (Bahia Grass) pasture for cattle grazing. Avian surveys conducted on reclaimed mined sites between 1995 and 2005 suggest, however, that Florida Burrowing Owls do not recolonize these sites (Concoby 2006a). Translocation has been used as a management tool for relocating Burrowing Owls to suitable habitat in California, Arizona, British Columbia, Oregon, and Washington (Delevoryas 1997, Feeney 1997, Klute et al. 2003), and one of the vital components for translocation success is food availability at the recipient site. Prey remains identified in Florida Burrowing Owl stomachs (Bent 1938, Lewis 1973, Palmer 1896), regurgitated pellets (Hennemann 1980, Neill 1954, Palmer 1896, Wesemann 1986), and burrows (Hennemann 1980, Neill 1954, Nicholson 1954, Owre 1978, Wesemann 1986) indicate a broad diet, with major prey items consisting of invertebrates, especially arthropods (Cahoon 1885, Mrykalo et al. 2009, Rhodes 1892, Ridgeway 1874, Sprunt 1954). Given the potential habitat available for Burrowing Owls on reclaimed mined sites, coupled with the fact that invertebrates comprise a substantial prey of Burrowing Owls, our primary objectives were to (1) determine relative prey abundance/prey richness of invertebrates on non-mined (pre-translocation) and reclaimed mine (translocation) sites, and (2) quantify the diet of Florida Burrowing Owls inhabiting these two areas. Mushinsky and McCoy (2001) reported that reclaimed mine sites generally contain fewer vertebrates for approximately 3 years following reclamation. Using this as a proxy for invertebrate abundance and considering that at least 15 years have elapsed from the time that the translocation site was initially mined, we hypothesized that arthropod abundance/richness on the pre-translocation and translocation sites would be equal. Methods The study was conducted from 15 May 2005 to 15 May 2006 at 3 locations: 2 pre-translocation (donor) sites, and 1 translocation (recipient) site. The pretranslocation sites contained 9 pairs of Florida Burrowing Owls which were later translocated. The pre-translocation sites were never mined and contained improved pastures composed of Bahia Grass and natural soil. The translocation site was a reclaimed phosphate mine converted to improved Bahia Grass pasture. The translocation site had been mined a minimum of 15 years before this project. All study sites contained third-order tributaries (creeks), and/or ephemeral wetlands within 500 m of burrows. Since these pastures had been ditched and drained for cattle use, the ephemeral wetlands were depressions that maintained drainage in these areas. The pre-translocation (donor) sites spanned two counties and were located on Fort Lonesome East, Mining Units 16 and 17, east of SR 39, Hillsborough County, FL; and Fort Green Mine, Manatee County Addition, Hardee County, FL. These areas consisted of approximately 580 ha of typical improved pasture. R.J. Sarno, P.A. Nixon, B.K. Mealey, 2012 R.E. Concoby, R.J. Mrykalo, and M.M. Grigione 757 The translocation (recipient) site contained artificial burrow systems, and was a 239-ha parcel located at Fort Green Mine, Polk County, FL. The translocation site was designated as the Fort Green Mine Special Reclamation Project Area and was located approximately 8 km southwest of the Fort Lonesome and Fort Green Mine sites (Fig. 1). A total of 9 release enclosures were designed, constructed, and installed on the translocation site. Enclosures were modified from those used to translocate Burrowing Owls at the Wild at Heart Rehabilitation Center, Cave Creek, AZ. Enclosures were constructed from 1.27-cm schedule 40 PVC pipe frame that was supported by wooden poles. The frame was covered with plastic cloth used for shading cattle. Each enclosure was 8 m x 8 m x 3 m high. Within each enclosure, R. Concoby (2006b) placed a single T-perch constructed from untreated 5.1-cm x 10.2-cm lumber. Artificial burrow systems were constructed to mimic natural burrows for translocated owls. Water bowls and a 45.7-cm x 45.7-cm food board were positioned to allow ease of access for all owls. Owls were provided 8–10 crickets and 2 mice/burrow/day. Birds were released after 18 days. Fifteen burrowing owls were successfully translocated. This effort resulted in nesting by 4 breeding pairs and the fledging of 9 juveniles that were produced from the original translocation of the 4 breeding pairs. Relative prey abundance and richness We define relative abundance as the mean number of arthropods/family (or order)/site. Relative richness is defined as the total number of arthropod families (or orders)/site. We trapped each study site 2 times each month for 2 days during each trapping occasion in order to assess relative abundance and richness of Figure 1. Location of the Fort Green and Fort Lonesome Mining Units that contained the pre-translocation (donor) and translocation (recipient) sites for Florida Burrowing Owls, 15 May 2005 to 15 May 2006. 758 Southeastern Naturalist Vol. 11, No. 4 potential prey items. We set 10 pitfall traps (i.e., 10 coffee cans, 15.24 x 17.8 cm, buried flush with the ground) at each study site during each trapping occasion. Each can contained 2.54 cm of soapy water in the bottom to prevent the escape of insects (Wesemann 1986). Two pitfall traps were placed approximately 200 m from 5 randomly selected burrows. Orientation (i.e., north, south, east, and west) of insect traps from enclosures were obtained from a random number generator. At the translocation site prior to translocation, we placed traps randomly within the predetermined relocation areas by constructing a grid and generating random x- and y-coordinates. All arthropods were counted and identified to the lowest taxonomic group (family or order) at each site (Bland and Jaques 1978). Relative abundance and relative richness on the two non-mined pre-translocation sites were combined for analyses. The total number of trapped insects from each site/trapping session was normalized using a square-root transformation. We examined relative prey abundance using an independent sample’s t-test to compare the mean number of arthropods/family (or order)/site. For comparisons of prey abundance between sites we utilized the Holm’s sequential Bonferroni correction (Holm 1979) in order to reduce the probability of a type I error. Prey richness was analyzed using a chi-square goodness-of-fit test on the total number of arthropod families (or orders) trapped/site (Sokal and Rohlf 1994). Diet analysis Diet was determined from regurgitated pellets that were collected from each site. Regurgitated pellets were collected up to 5 m from each active burrow at least twice each month. Following field collection, pellets were dried in an incubator at 70 °C for 48 hrs and dismantled. Prey contents were identified using a 10 x 3 dissecting stereomicroscope. We separated contents by prey type using easily identifiable exoskeletal sections, such as mandibles, head capsules, and elytra (Gleason and Craig 1979, Mrykalo 2005, Wesemann 1986). Arthropod exoskeleton parts were identified to the lowest practical taxon by comparing them to previously identified specimens at the University of South Florida. Vertebrate items were identified by referencing a specimen collection at the Florida Museum of Natural History. The total number of arthropods and vertebrate prey remains in pellets was summed to indicate the frequency of prey items in the diet (Wakeley 1978). As for relative abundance and relative richness, the data from the two non-mined pre-translocation sites were combined for analyses. We performed a square-root transformation on the total number of arthropods and vertebrates in each family (or order)/sample in order to normalize the data. Normalized totals were analyzed using independent sample’s t-test in order to compare means among sites (Sokal and Rohlf 1994). Holm’s sequential Bonferroni correction (Holm 1979) was utilized to reduce the probability of committing a type I error when comparing diet among owls in pre-translocation and translocation sites. A Spearman’s rank-order correlation (Sokal and Rohlf 1994) was used to compare the monthly means of trapped prey items/family/site to monthly means of prey items/family/site found in pellets. All data were analyzed using SAS software (SAS Institute, Inc. 2001). R.J. Sarno, P.A. Nixon, B.K. Mealey, 2012 R.E. Concoby, R.J. Mrykalo, and M.M. Grigione 759 Results Prey richness There were no appreciable differences in relative prey richness between the pre-translocation (non-mined) site and the translocation (reclaimed mine) site, as we trapped a total of 21 different types of arthropods on the pre-translocation site and 15 on the translocation site (χ 2 = 1.00, df = 1, P = 0.32; Table 1). Prey abundance As a result of the sequential Bonferroni control, the critical P-value at which independent samples t-tests were no longer considered significant for prey abundance was P > 0.025. The pre-translocation site contained significantly more insects from the families Carabidae, Gryllidae, Cicadellidae, Acrididae, Dryopthoidae, Scarabaeidae, and Clubionidae, than did the translocation site (Table 2). Diet We collected 193 pellets from the pre-translocation site and 29 from the translocation site. Forty-eight percent (10 of 21) of prey taxa that we trapped were actually present in pellets. Prey items present in pellets but not in traps included the families Cambaridae (crayfish), Curculionidae (beetles), Emydidae (turtles), Ranidae (frogs), Spiraxidae (snails), and Soricidae (shrews). The Spearman’s rank correlation revealed no significant correlation (ρ = 0.59, n = 10, P > 0.05) between diet and prey abundance for any arthropod family. The critical P-value at which independent samples t-tests were no longer considered significant for diet was P > 0.025 Table 1. Insects trapped on three Florida Burrowing Owl study areas located on the Fort Green Mine Site, Polk/Manatee counties, FL, May 2005–May 2006. P = present, X= not present. Insect family Pre-Translocation Translocation Acrididae P P Carabidae P P Cicadellidae P P Clubionidae P P Coreidae P X Dryophthoridae P P Gelastocoridae P P Gryllidae P P Gryllotalpidae P P Hymenoptera P P Labiduridae P P Lepidoptera P P Lycosidae P P Mutillidae P P Pentatomidae P X Pseudophasatidae P X Reduviidae P X Scarabaeidae P P Tettigoniidae P P Theridiidae P X 760 Southeastern Naturalist Vol. 11, No. 4 Owls on the pre-translocation site consumed significantly more insects from the families Gryllidae and Scarabaeidae, while owls on the translocation site consumed more insects from the families Carabidae and Curculionidae (Tables 3, 4). Other than this, the diet of all other prey items was similar. Table 2. Prey abundance of Florida Burrowing Owls by site in Polk and Manatee counties, FL, May 2005–May 2006. Number of sample periods (n) equals 16. Degrees-of-freedom for all analyses equals 30. Pre-translocation Translocation Species Mean (±SE) Mean (±SE) T-statistic P-value Carabidae 2.6 ± 0.40 1.1 ± 0.25 3.20 0.003 Gryllidae 5.2 ± 0.53 1.4 ± 0.51 5.09 <0.001 Cicadellidae 0.7 ± 0.15 0.1 ± 0.06 3.83 <0.001 Acrididae 4.4 ± 0.61 1.8 ± 0.46 3.43 0.002 Dryopthoridae 0.7 ± 0.18 0.2 ± 0.10 2.46 0.020 Scarabaeidae 13.1 ± 1.84 3.5 ± 1.08 4.51 <0.001 Clubionidae 8.8 ± 1.07 2.6 ± 0.48 5.28 <0.001 Gastrophyne 2.6 ± 0.72 0.0 3.56 0.001 Table 4. Number and percent total of prey items (identified to family) in pellets of Florida Burrowing Owls by study site, Fort Green Mine Site, Polk/Manatee counties, FL, May 2005–May 2006. Pre-translocation Translocation Family Number Percent Number Percent Acrididae 1174 21.5 128 19.7 Cambaridae 3 0.1 0 0.0 Carabidae 801 14.7 145 22.3 Clubionidae 134 2.4 15 2.3 Curculionidae 79 1.4 27 4.2 Emydidae 2 0.04 1 0.2 Gryllidae 1318 24.1 138 21.2 Gryllotalpidae 92 1.7 10 1.5 Labiduridae 430 7.9 65 10.0 Lycosidae 42 0.7 0 0.0 Microhylidae 9 0.2 0 0.0 Ranidae 5 0.09 0 0.0 Scarabaeidae 1328 24.3 110 16.9 Soricidae 3 0.05 1 0.2 Spiraxidae 6 0.2 4 0.6 Tettigoniidae 37 0.8 7 1.1 Total 3297 100 651 100 Table 3. Diet of Florida Burrowing Owls by site in Polk and Manatee counties, FL, May 2005–May 2006. Number of sample periods is (n) equals16. Degrees-of-freedom for all analyses equals 30. Pre-translocation Translocation Species Mean (±SE) Mean (±SE) T-statistic P-value Carabidae 4.1 ± 0.10 5.8 ± 0.10 7.75 <0.001 Curculionidae 0.4 ± 0.10 1.1 ± 0.10 7.32 <0.001 Gryllidae 6.8 ± 0.10 5.5 ± 0.09 2.36 0.020 Scarabaeidae 6.9 ± 0.14 4.4 ± 0.14 5.60 <0.001 R.J. Sarno, P.A. Nixon, B.K. Mealey, 2012 R.E. Concoby, R.J. Mrykalo, and M.M. Grigione 761 Discussion Relative prey richness among sites did not vary noticeably. Although we trapped the greatest number of distinct arthropod groups on the pre-translocation (non-mined) site, 6 of the families were absent from the diet of owls. The insect families Carabidae, Curculionidae, Gryllidae, and Scarabaeidae were the most important diet components of owls in our study, and many of these same families appear to be important in the diet of A. c. hypugaea (Bonaparte) (Western Burrowing Owl; Chipman et al. 2008, Marti 1974, Thomspon and Anderson 1988). Only 10 of 21 prey types that we trapped were actually present in owl pellets. Except for the family Microhylidae, all remaining non-arthropod prey remains in pellets were neither trapped nor observed dead outside of burrows. Perhaps our trapping protocol prevented capture of these particular prey species and/or owls regularly hunted in different habitats (Mrykalo et al. 2007, Sissons and Scalise 2001). For example, it appears that owls were hunting in aquatic habitats (i.e., creeks, ephemeral wetlands, and drainage ditches) due to the remains of frogs (Ranidae and Microhylidae), turtles (Emydidae), and crayfish (Ca mbaridae). The similarity in prey abundance and diet between the pre-translocation and translocation sites suggests that reclaimed mines may serve as adequate refugia for Florida Burrowing Owls. However, further studies are needed that encompass a larger number of non-mined versus reclaimed sites to adequately determine if reclaimed mined sites provide suitable foraging habitat for Florida Burrowing Owls. Given that owl diet can differ by season and sex (Hall et al. 2009, Marti 1974, York et al. 2002), it is important that any potential translocation site contain sufficient numbers of potential invertebrate and vertebrate prey that owls would normally encounter while foraging. Additionally, since owls are central-place foragers, and males generally forage farthest from burrows (Thompson and Anderson 1988), there is a need for adequate feeding areas at greater distances from burrows. Therefore, the juxtaposition of translocation sites to a mosaic of different habitat (at varying distances from the burrow) may increase the likelihood of a successful translocation from a foraging perspective, given that owls appear to be opportunistic feeders (Grimm et al. 1985). Population projections prepared by the GeoPlan Center at the University of Florida indicate that Florida’s human population will double in size from 17.9 million people to 35.8 million people between 2005 and 2060. As a result of human population growth, nearly 2,833,000 ha of land will be developed. Of this, approximately 1,012,000 ha of the highest priority land for conservation is likely to be directly impacted (Barnett and Dobshinsky 2007). If viable Florida Burrowing Owl populations are to be maintained, then translocation is likely to become a more common conservation tool. Therefore, we suggest that wildlife managers and/or researchers ascertain whether reclaimed sites that are targeted for translocation of Florida Burrowing Owls support comparable numbers and variety of invertebrate/vertebrate communities compared to non-mined sites. 762 Southeastern Naturalist Vol. 11, No. 4 Acknowledgments We thank M. Baughman, B. Brooks, and R. Morris for assistance in the field. The following agencies contributed to the success of this translocation: US Fish and Wildlife Service, Florida Fish and Wildlife Conservation Commission, Florida Department of Environmental Protection, Hillsborough County Upland Habitat Protection Division, Polk County Environmental Department, Hardee County Biological Staff, IMC Phosphates Company, Raptor Management Consultants, Biological Research Associates, Quest Ecology, Penn Pro Engineering and the Wild at Heart Rehabilitation Center (Arizona). Permission to translocate owls was granted to R.E. Concoby by the US Fish and Wildlife Service and the Florida Fish and Wildlife Conservation Commission. Capture and tagging permits were issued to L. Walton, R.E. Concoby, B.K. Mealey, and R.J. Sarno. Literature cited Barnett, J., and A. Dobshinsky. 2007. An alternative future: Florida in the 21st century 2020 2040 2060. University of Pennsylvania, Philadelphia, PA. 180 pp. Bent, A.C. 1938. Life histories of North American birds of prey. Part 2. US National Museum Bulletin. No 170. Washington, DC. Birnhak, B.I., and J.P. Crowder. 1974. An evaluation of the extent of vegetative habitat alteration in South Florida 1943–1970. US Department of the Interior, Bureau of Sport Fisheries and Wildlife, Atlanta, GA. PB-231-621. Bland, R.G., and H.E. Jaques. 1978. How to Know the Insects, 3rd Edition. MacGraw- Hill, New York, NY. 205 pp. Cahoon, J.C. 1885. The Florida Burrowing Owl (Speotyto cunicularia floridana). Ornithologist and Oologist 10:21. Chipman, E.D., N.E. McIntyre, R.E. Strauss, M.C. Wallace, J.D. Ray, and C.W. Boal. 2008. Effects of human land use on Western Burrowing Owl foraging and activity budgets. Journal of Raptor Research 42:87–98. Concoby, R.E. 2006a. 1995–2006 Mosaic Burrowing Owl survey and banding report. US Fish and Wildlife Service, Tallahassee, FL. Concoby, R.E. 2006b. Mosaic experimental Burrowing Owl translocation project I posttranslocation report. Unpublished resport submitted to the Florida Fish and Wildlife Conservation Commission, Tallahassee, FL. Delevoryas, P. 1997. Relocation of Burrowing Owls during courtship period. Pp. 138– 144, In J.L. Lincer and K. Steenhof (Eds.). Proceedings of the First International Burrowing Owl Symposium. Journal of Raptor Research Report 9. Ewel, J.J. 1990. Introduction. Pp. 3–10, In R.L. Meyers and J.J Ewel (Eds.). Ecosystems of Florida. University of Central Florida Press, Orlando, FL. Feeney, L.R. 1997. Burrowing Owl site tenacity associated with relocation efforts. Pp. 132–137, In J.L. Lincer and K. Steenhof (Eds.). Proceedings of the First International Burrowing Owl Symposium. Journal of Raptor Research Report 9. Florida Administrative Code. Chapter 62C-16: Bureau of Mine Reclamation: Mandatory phosphate mine reclamation. Available online at https://www.flrules.org/gateway/ ChapterHome.asp?Chapter=62C-16. Accessed 13 October 2008. Florida Department of Environmental Protection. 2005. Bureau of Mine Reclamation: Rate of reclamation report. Available online at http//:www.dep.state.fl.us/legal/Final_ Orders/2007/dep07-0612.doc. Accessed 12 October 2008. R.J. Sarno, P.A. Nixon, B.K. Mealey, 2012 R.E. Concoby, R.J. Mrykalo, and M.M. Grigione 763 Florida Department of State. 1979. 39-27.05 Designation of species of special concern. Division of Library and Information Services, Tallahassee, FL. Florida Department of Transportation. 1999. Florida land use, cover, and forms classification system. Surveying and Mapping Office geographic mapping section handbook 3rd edition. Tallahassee, FL. 93 pp. Available online at http://www.dot.state.fl.us/ surveyingandmapping/Manuals/fluccmanual.pdf. Florida Fish and Wildlife Conservation Commission. 2011. Florida Burrowing Owl biological status review report. Tallahassee, FL. 16 pp. Available online at http://myfwc. com/media/2273286/FL-Burrowing-Owl-BSR.pdf. Florida Statutes. Chapter 378: Land reclamation. Available online at http://www.leg. state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&URL=Ch0378/titl0378. htm&StatuteYear=2008&Title=->2008->Chapter 378. Accessed 12 October 2008. Gleason, R.L., and T.H. Craig. 1979. Food habits of Burrowing Owls in southeastern Idaho. Great Basin Naturalist 39:274–276. Grimm, D.M., J.T. Ratti, and R. Friesz. 1985. Effects of ash on food habits of Burrowing Owls at Moses Lake, Washington. Northwest Scientist 59:40–44. Hall, D.B., P.D. Greger, and J.R. Rosier. 2009. Regional and seasonal diet of the Western Burrowing Owl in south-central Nevada. Western North American Naturalist 69:1–8. Hennemann, W.W., III. 1980. Notes on the food habits of the Burrowing Owl in Duval County, Florida. Florida Field Naturalist 8:24–25. Holm, S. 1979. A simple sequentially rejective multiple test procedure. Scandinavian Journal of Statistics 6:65–70. Klute, D.S., L.W. Ayers, M.T. Green, W.H. Howe, S.L. Jones, J.A. Shaffer, S. Sheffield, R. Zimmerman, and T.S. Zimmerman. 2003. Status assessment and conservation plan for the Western Burrowing Owl in the United States. US Department of Interior, Fish and Wildlife Service, Biological Technical Publication FWS/BTP-R6001-2003, Washington, DC. Lewis, J.C. 1973. Food habits of Florida Burrowing Owls. Florida Field Naturalist 1:27–29. Marti, C.D. 1974. Feeding ecology of four sympatric owls. Condor 76:45–61. Mealey, B.K. 1997. Reproductive ecology of the Burrowing Owl, Speotyto cunicularia floridana, in Dade and Broward counties, Florida. Journal of Raptor Research Report 9:7479. Mrykalo R. 2005. The Florida Burrowing Owl in a rural environment: Breeding habitat, dispersal, post-breeding habitat, behavior, and diet. University of Southern Florida Graduate School Theses and Dissertations. Available online at http://scholarcommons. usf.edu/etd/779. Mrykalo, R., M.M. Grigione, and R.J. Sarno. 2007. Home range and dispersal of juvenile Florida Burrowing Owls. Wilson Journal of Ornithology 119:275–279. Mrykalo, R., M.M. Grigione, and R.J. Sarno 2009. Comparison of available prey and diet of Florida Burrowing Owls in urban and rural environments: A first study. The Condor 111:556–559. Mushinsky, H.R., and E.D. McCoy. 2001. Habitat factors influencing the distribution of small vertebrates on unmined and phosphate-mined flatlands in central Florida, and a comparison with unmined and phosphate-mined uplands. Florida Institute of Phosphate Research, Bartow, FL. Neill, W.T. 1954. Notes on the Florida Burrowing Owl. Florida Naturalist 27:67–70. 764 Southeastern Naturalist Vol. 11, No. 4 Nicholson, D.J. 1954. The Florida Burrowing Owl: A vanishing species. Florida Naturalist 27:3–4. Owre, O.T. 1978. Florida Burrowing Owl. Pp. 97–99, In H.W. Kale III (Ed.). Rare and Endangered Biota of Florida. Vol. II. Birds. Presses of Florida, Gainesville, FL. 392 pp. Palmer, W. 1896. On the Florida Ground Owl (Speotyto floridana). Auk 13:99–108. Rhodes, S.N. 1892. The breeding habits of the Florida Burrowing Owl (Speotyto cunicularia floridana). Auk 9:1–8. Ridgeway, R. 1874. Discovery of a Burrowing Owl in Florida. American Sportsman 4:216–217. Sas Institute, Inc. 2001. SAS/STAT User’s Guide. Release 8.0. Cary, NC. Sissons, R.A., and K.L. Scalise. 2001. Nocturnal foraging habitat use by male Burrowing Owls in a heavily cultivated region of southern Saskatchewan. Journal of Raptor Research 35:304–309. Sokal, R.R., and F.J. Rohlf. 1994. Biometry: The Principles and Practice of Statistics in Biological Research, 3rd Edition. Freeman, San Francisco, CA. 887 pp. Sprunt, A., Jr. 1954. Florida Bird Life. Coward-McCann, Inc., and The National Audubon Society, New York, NY. 579 pp. Thompson, C.D., and S.H. Anderson. 1988. Foraging behavior and food habits of Burrowing Owls in Wyoming. Prairie Naturalist 20:23–28. Wakeley, J.S. 1978. Activity budgets, energy expenditures, and energy intakes of nesting ferruginous hawks. Auk 95:667–676. Wesemann, T. 1986. Factors influencing the distribution and abundance of Burrowing Owls (Athene cunicularia) in Cape Coral, Florida. M.Sc. Thesis. Appalachian State University, Boone, NC. 86 pp. York, M.M., D.K. Rosenberg, and K.K. Sturm. 2002. Diet and food-niche breadth of Burrowing Owls (Athene cunicularia) in the Imperial Valley, California. Western North American Naturalist 62:280–287.